In electrophotographic applications such as xerography, a charge retentive surface is electrostatically charged and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder referred to as "toner". Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is well known and useful for light lens copying from an original and printing applications from electronically generated or stored originals, where a charged surface may be imagewise discharged in a variety of ways.
Although a preponderance of the toner forming the image is transferred to the paper during the transfer step, some toner invariably remains on the charge retentive surface, it being held thereto by relatively high electrostatic and/or mechanical forces. Additionally, paper fibers, Kaolin and other debris have a tendency to be attracted to the charge retentive surface. It is essential for optimum operation that the toner remaining on the surface be cleaned thoroughly therefrom.
Blade cleaning is a highly desirable method for removal of residual toner from a charge retentive surface. In such an arrangement, a blade is provided and supported adjacent to the charge retentive surface with a blade edge chiseling toner from contact with the surface. Subsequent to removal from the surface, toner is transported away from the blade area by a toner transport arrangement. Blade cleaning arrangements are very effective, and inexpensive relative to other cleaning devices, and serviceable over the device lifetime. Variations in lubricants and materials allow the use of blade cleaning at relatively high surface velocity.
Removal of accumulating toner from the blade area may be accomplished in a variety of ways, each dependent on the machine arrangement. While a cleaning arrangement for a more or less vertical surface may allow toner to simply fall from the blade area to a toner transport device, positioning the cleaning arrangement on a horizontal surface, sometimes referred to as twelve o'clock cleaning, requires direct removal of toner from the surface. Possible methods of transporting cleaned toner from the surface include air flow or vacuum transport, electric or magnetic transport, or mechanical transport. Air flow or vacuum transport offers an effective, but costly manner of moving toner. Electrical or magnetic systems, such as, for example, U.S. Pat. No. 4,398,820 to Thayer, are also costly, and depend on a well controlled charge state of the toner. Mechanical transports offer the best compromise for cost and reliability.
Typically, toner might be removed from the blade area either by a brush arrangement which transports toner generally vertically from the surface to a transport arrangement for removal to another area, such as shown, for example, in U.S. Pat. No. 4,427,289 to Oda, or directly by an augering arrangement, such as shown, for example, in U.S. Pat. No. 4,329,044 to Kitajium et al. and U.S. Pat. No. 3,917,398 to Takahashi et al., which move toner off the edge of the photoreceptor with an augering arrangement, or U.S. Pat. No. 3,951,542 to Ito et al. which similarly moves toner by an augering arrangement to the edge of a photoreceptor, to a multi-vaned direction changing member. Movement of the toner off the edge of the photoreceptor creates significant problems in toner contamination through the machine. For this reason, it is desirable when possible to remove toner generally vertically from the charge retentive surface.
Brush toner removal arrangements, such as shown in U.S. Pat. No. 4,427,289 to Oda, while in use, create significant problems. Toner is accumulated in the brush fibers, requiring periodic removal for cleaning or replacement. Detoning rolls must be provided to remove toner from the brush. The time that toner is in contact with the brush fibers must be minimized to avoid triboelectric charge transfer between toner and the brush fibers, which varies the removability of the toner. Additionally, the brush itself is not an inexpensive device to manufacture.
Thayer, "Photoreceptor Toner Cleaning Member," Xerox Disclosure Journal, Vol. 4, No. 5, September/October 1979 discloses a ribbed cleaning member directly contacting a photoreceptor surface to wipe and flick toner therefrom. The surface is supported on a compressible core so that the member may be compressed in contact with photoreceptor. U.S. Pat. No. 4,360,944 to Iwai et al. shows a toner transport direction changing device including a single elastic plate member which moves toner through a housing from an output end of an auger to an input for a belt conveyor. U.S. Pat. No. 4,571,066 to Morrison describes a toner removal arrangement utilizing a compliant foam roll for removal of toner from the imaging surface, and a toner transport grid form on a non-imaging area of the photoreceptor for removal of the toner from the compliant foam roll for return on the photoconductive drum to the developing station. U.S. Pat. No. 4,323,306 to Ito et al. shows a cleaning device for removal of remaining developer from the surface of an image bearing member including a screw member operable to move toner away from a chiseling blade member in contact with the image bearing member. DE 32 07-900A to Kaspers shows an plastic cover of a cleaning roller formed with a star shaped interior conforming to vanes on a supporting inner core.